Human Adequate Lighting in Optimal Healing Environments – Measuring Non-visual Light Effects of a LED Light Source According to German Draft Pre-standard DIN SPEC 5031-100:2012

Abstract

Abstract. Exposing human beings to natural light has many empirically and experimentally corroborated effects on health, well-being and quality of life. One important effect is the entrainment of the human "master clock" to the 24h rhythm of the solar day. In contrast, being surrounded by darkness during the night increases blood levels of melatonin, the brain derived "sleep hormone", and thus signaling other organs aside from the brain. However, in contrast to earlier times, particularly in urban areas distinct periods of the day marked by bright and dark light conditions are scarce, as modern lifestyle has changed and artificial lighting is present in cities on a 24 hour basis. In addition to the merely "visual" effects, light also exhibits non-visual, but biologically relevant (time, spatial, quality and quantity dependent) effects, that are mediated by specialized cells in the eye. These non-visual effects, such as the suppression of melatonin during nighttime may potentially be regarded as a severe risk factor to human health. Due to the discovery of the relationship of light exposure and melatonin suppression, studies have been conducted to evaluate which properties of light are most effective in suppressing melatonin.In 2009 a first pre-standard for determining the non-visual effects of light mediated through the eye was established by the German Institute of Standardization (DIN). In this paper we describe, according to the standard, one approach to assess melatonin suppressing potential of light sources on the basis of mathematical algorithms that can be utilized as a conceptual platform for planning visual and non-visual effective lighting for optimal healing environments.